spend a penny (
http://definr.com/spend a penny)
v : eliminate urine; "Again, the cat had made on the expensive
rug" [syn:
make,
urinate,
piddle,
puddle,
micturate,
piss,
pee,
pee-pee,
make water,
relieve oneself,
take a leak,
wee,
wee-wee,
pass water]